1. Field of the Invention
The present invention relates to novel (meth)acrylic acid ester, and an activation energy ray curing composition using the same, and an inkjet recording ink using the same.
2. Description of the Related Art
As a method for forming an image on a recording medium, such as paper, there are various methods, such as electrophotography, sublimation recording, thermal transfer recording, and inkjet recording. Among them, the inkjet recording has high efficiency in ink consumption, and therefore is excellent in resources saving, and can keep an ink cost per unit recording low. However, there are various problems when an aqueous ink is used. There are inks using organic solvent instead of water, but these inks also have different problems.
Because of the reasons as mentioned, attentions have recently been attracted to inkjet recording using an activation energy ray-curing ink. The activation energy ray-curing ink has been described as a UV ray-curing ink composition in various literatures, and documents. Typically, the activation energy ray-curing ink contains a polymerization initiator and monomers as essential components, and optionally contains substances such as a pigment, oligomers, polymers, and a sensitizing agent (Optical Applied Technologies and Materials Dictionary (edited by the editorial committee of Optical Applied Technologies and Materials Dictionary, Kabushikigaisha Sangyo Gijutsu Service center, published in 2006); The latest/Optimization of UV cured resin (Technical Information Institute Co., Ltd., published in 2008) etc.).
As the monomer component, a plurality of monomers are used in view of curing speed (sensitivity), viscosity of an ink, and properties of a film after curing. It is common that a low molecular weight monomer that has a molecular weight of 700 or smaller, has low viscosity, and is excellent in reactivity, and a polyfunctional high molecular weight monomer are used in combination. Since the monomers are a main component constituting about 80% by mass of the inkjet recording ink, a research on a formulation (combination) thereof has been actively conducted as well as a development of a material thereof.
For example, disclosed are an invention using an ester or amide compound of tri- or higher functional (meth)acrylic acid having an alkylene oxide group in a molecule thereof (Japanese Patent Application Laid-Open (JP-A) No. 2007-231231), an invention using a combination of an ester or amide of tri- or higher functional (meth)acrylic acid having an alkylene oxide group in a molecule thereof and an ester or amide of monofunctional (meth)acrylic acid having C6-C12 alkyl site (JP-A No. 2007-231233), an invention using a combination of an aliphatic (meth)acrylate compound containing a secondary hydroxyl group and a compound containing a nitrogen atom and a polymerizable unsaturated bond in a molecule thereof (JP-A No. 2009-67926), and an invention using a polymerizable compound containing a polymerizable unsaturated bond and an amino group in a molecule thereof (JP-A No. 2009-144057).
Moreover, use of a monomer compound having a urethane structure has been proposed, and examples thereof include an invention including urethane acrylate oligomers (JP-A Nos. 2006-257155, and 2009-249561). However, these urethane acrylate oligomers have the NH structure of a hydrogen bond, and have high molecular weights, and therefore have high viscosity. Accordingly, the urethane acrylate oligomer is not suitable for use in an inkjet recording ink, and it is used as a mixture with another (meth)acrylic acid monomer of low viscosity.
As for a low molecular weight (meth)acrylic acid monomer having a urethane structure and having a molecular weight of 700 or smaller, disclosed is an ink for color filter, which uses a methacrylic acid monomer having a urethane structure including an NH structure (JP-A No. 2010-181677), but it is also not suitable for an inkjet recording ink because the viscosity thereof is high.
Meanwhile, urethane (meth)acrylate or urethane (meth)acrylate oligomers having an NH structure have been used in various activation energy ray-curing compositions (JP-A Nos. 62-285959 and 63-054416) other than inkjet recording inks. However, these also increase the viscosity thereof, and therefore there is a restriction due to the viscosity depending on intended use thereof, or it is necessary to use in combination with a monomer of low viscosity.
Further, for the purpose of improving properties such as high curing ability, flexibility of a cured film, solvent resistance and adhesion with a base material, proposed are an invention using a monomer having an alicyclic structure (JP-A No. 2007-138118), an invention using a monomer having a heterocyclic structure such as dioxolane and dioxane (JP-A No. 2007-177174), and an invention using a plurality of monomers each having two or more alicyclic structures, heterocyclic structures, or aromatic ring structures (JP-A No. 2009-179681).
However, these monomer compounds tend to be evaporated, and therefore they cause discomfort due to odor distinctive to the monomers. Moreover, there is a problem that an alicyclic ring or aromatic ring in the structure does not give sufficient adhesion.